The present disclosure relates to roll bending machines having three or four rolls, which are well known in the metal fabricating industry for rolling metal plate into cylinders, obrounds and cone shapes. This type of machine uses hydraulic cylinders to change the relative position between the various rolls of the machine, and also hydraulic motors to rotate the rolls, such that plates can be formed in any desired shape.
The hydraulic systems of such machines commonly utilize a centrally located hydraulic manifold on which proportional valves, counterbalance valves, solenoid valves, flow control valves, oil pressure sensors and the like are mounted to operate hydraulic cylinders or motors that power and position gripping and bending rolls. In certain machines, the hydraulic manifolds are manufactured to National Fluid Power Association (NFPA) standard dimensions or International Standard Organization (ISO) standard dimensions and can be purchased from catalogs of various manufacturers. Similarly, the cylinders are manufactured to NFPA or ISO standard dimensions and can be purchased from catalogs form various manufacturers.
In a typical roll bending machine, pressurized hydraulic fluid is provided from a hydraulic pump into a manifold, which contains valves and other flow control devices that are fluidly connected, via tubes and hoses, to the various actuators of the machine. The various actuators are selectively activated to advance the plate and position the rolls such that a plate is bent to a desired radius. However, various variables may affect the final shape of the plate, which is typically addressed by experienced operators adjusting the various settings of the machine until a desired plate shape is produced. The variability in the plate shape can result from any number of factors such as the thickness and hardness of the plate, flexing in the bending or gripping rolls of the machine, and others.
In the past, plate roll bending machine manufacturers have attempted to improve the roll process in terms of accuracy in the shape of the bent plate while also minimizing undesirable effects in different ways. One such example can be seen in U.S. Pat. No. 5,890,386 to Davi, which issued on Apr. 6, 1999. Davi describes a roll bending machine in which typical undesirable effects in the bent plate, which are commonly referred to as trumpeting or barreling, are sought to be controlled. These effects, which produce cylinders having their seam either diverging or converging, as shown in FIGS. 5 and 6 of Davi, can result from bending or flexing of the machine rolls during a forming process. In Davi, the rolls are supported by devices (31, FIG. 1 that axially support the bending roll to prevent flexing. While the system configuration of Davi may be partially effective in preventing plate deformation during a bending process due to bending roll flexing, it will not typically account for other factors affecting plate rolling and may partially contribute to achieving a desired bent plate diameter. Moreover, the support members may adversely affect the finish of the rolled plate, especially along an area of contact on the outer surface.